Each of the above-identified patent application is incorporated herein by reference.
The present invention relates to apparatus and methods for processing substrates such as semiconductor substrates for use in IC fabrication or panels (e.g., glass, plastic, or the like) for use in flat panel display applications. More particularly, the present invention relates to improved plasma processing systems that are capable of processing substrates with a high degree of processing uniformity across the substrate surface.
Plasma processing systems have been around for some time. Over the years, plasma processing systems utilizing inductively coupled plasma sources, electron cyclotron resonance (ECR) sources, capacitive sources, and the like, have been introduced and employed to various degrees to process semiconductor substrates and display panels.
In a typical plasma processing application, the processing source gases (such as the etchant gases or the deposition source gases) are introduced into the chamber. Energy is then provided to ignite a plasma in the processing source gases. After the plasma is ignited, it is sustained with additional energy, which may be coupled to the plasma in various well-known ways, e.g., capacitively, inductively, through microwave, and the like. The plasma is then employed in the processing task, e.g., to selectively etch or deposit a film on the substrate. Plasma processing systems in general are well known in the art and the reference literature is replete with details pertaining to various commercially available systems. Thus general principles pertaining to plasma processing will not be discussed in great detail here for brevity""s sake.
In processing the substrates, one of the important parameters that process engineers strive to improve is processing uniformity. In the etch environment, for example, etch uniformity is an important determinant of yield, i.e., a high level of etch uniformity tends to improve the percentage of defect-free processed substrates, which translates into lower cost for the manufacturer. As the term is employed herein, etch uniformity refers to the uniformity of the entire etch process across the substrate surface including etch rate, microloading, mask selectivity, underlayer selectivity, critical dimension control, and profile characteristics like sidewall angle and roughness. If the etch is highly uniform, for example, it is expected that the etch rates at different points on the substrate tend to be substantially equal. In this case, it is less likely that one area of the substrate will be unduly over-etched while other areas remain inadequately etched. In addition, in many applications these stringent processing requirements may be contradictory at different stages during the substrate processing. Often this is due to the presence of multiple films that must be processed with dramatically different plasma processing requirements. For example, the gas pressure, plasma density and chemistry may be required to dramatically change while processing a single substrate to achieve the desired processing performance.
In addition to processing uniformity, there also exist other issues of concern to the process engineers. Among the important issues to manufacturers is the cost of ownership of the processing tool, which includes, for example, the cost of acquiring and maintaining the system, the frequency of chamber cleaning required to maintain an acceptable level of processing performance, the longevity of the system components, and the like. Thus a desirable etch process is often one that strikes the right balance between the different cost-of-ownership and process parameters in such a way that results in a higher quality process at a lower cost. Further, as the features on the substrate become smaller and the process becomes more demanding (e.g., smaller critical dimensions, higher aspect ratios, faster throughput, and the like), process engineers are constantly searching for new methods and apparatuses to achieve higher quality processing results at lower costs.
The invention relates, in one embodiment, to a plasma processing system for processing a substrate which includes a single chamber, substantially azimuthally symmetric plasma processing chamber within which a plasma is both ignited and sustained for the processing. The plasma processing chamber has no separate plasma generation chamber. The plasma processing chamber has an upper end and a lower end.
The plasma processing system includes a coupling window disposed at an upper end of the plasma processing chamber and an RF antenna arrangement disposed above a plane defined by the substrate when the substrate is disposed within the plasma processing chamber for the processing. The plasma processing system also includes an electromagnet arrangement disposed above the plane defined by the substrate. The electromagnet arrangement is configured so as to result in a radial variation in the controllable magnetic field within the plasma processing chamber in the region proximate the coupling window and antenna when at least one direct current is supplied to the electromagnet arrangement. The radial variation is effective to affect processing uniformity across the substrate.
The plasma processing system additionally includes a dc power supply coupled to the electromagnet arrangement. The dc power supply has a controller to vary a magnitude of at least one direct current, thereby changing the radial variation in the controllable magnetic field within the plasma processing chamber in the region proximate the antenna to improve the processing uniformity across the substrate.
In another embodiment, the invention relates to a method for controlling processing uniformity while processing a substrate using a plasma-enhanced process. The method includes providing a plasma processing chamber having a single chamber, substantially azimuthally symmetric configuration within which a plasma is both ignited and sustained during the processing of the substrate, the plasma processing chamber having no separate plasma generation chamber.
The method also includes providing a coupling window disposed at an upper end of the plasma processing system and providing an RF antenna arrangement disposed above a plane defined by the substrate when the substrate is disposed within the plasma processing chamber for the processing. The method additionally includes providing an electromagnet arrangement disposed above the plane defined by the substrate. The electromagnet arrangement is configured so as to result in a radial variation in the controllable magnetic field within the plasma processing chamber in the region proximate the coupling window and antenna when at least one direct current is supplied to the electromagnet arrangement. The radial variation is effective to affect processing uniformity across the substrate.
Additionally, there is included providing a dc power supply coupled to the electromagnet arrangement, placing the substrate into the plasma processing chamber, flowing reactant gases into the plasma processing chamber, striking the plasma out of the reactant gases, and changing the radial variation in the controllable magnetic field within the plasma processing chamber in the region proximate the antenna to improve the process uniformity across the substrate.
In yet another embodiment, the invention relates to a plasma processing system for processing a substrate, which includes a single chamber, substantially azimuthally symmetric plasma processing chamber within which a plasma is both ignited and sustained for the processing. The plasma processing chamber has no separate plasma generation chamber. The plasma processing chamber has an upper end and a lower end.
The plasma processing system includes a coupling window disposed at an upper end of the plasma processing chamber, and an RF antenna arrangement disposed above a plane defined by the substrate when the substrate is disposed within the plasma processing chamber for the processing.
There is further included a first RF power supply coupled to the RF antenna, and a first magnet arrangement disposed above the plane defined by the substrate. The magnet arrangement is configured so as to result in a radial variation in the controllable magnetic field within the plasma processing chamber in the region proximate the coupling window and antenna due to magnetic field lines emanating from the magnet arrangement. The radial variation is effective to affect processing uniformity across the substrate.
Additionally, there is included a substrate support arrangement configured to support the substrate within the plasma processing chamber during the processing, and a second RF power supply coupled to the substrate support arrangement. The second RF power supply is controllable independently from the first RF power supply. Further, there is included means to vary the radial variation in the controllable magnetic field within the plasma processing chamber in the region proximate the antenna to improve the processing uniformity across the substrate.
These and other features of the present invention will be described in more detail below in the detailed description of the invention and in conjunction with the following figures.